JP3132918B2 - Red pigment and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red pigment and a method for producing the same, and more particularly to an improvement in a red pigment using an inorganic material and a method for producing the same.

[0002]

2. Description of the Related Art Red pigments are widely used in various fields such as cosmetics, vehicle paints, general paints, plastics, inks, synthetic leather, printing, miscellaneous goods, furniture, decorative articles, building materials, and general miscellaneous goods. As a conventional general red pigment,
Many of them use a red organic substance such as carmine, but have various drawbacks, such as discoloration and deterioration due to light, or safety problems remain. On the other hand, as an inorganic red pigment,
Those using red iron oxide are well known. That is, a flaky mica particle surface coated with red iron oxide, a mica particle surface coated with titanium dioxide and further coated with iron oxide, or a plate-shaped red iron oxide is used. These inorganic red pigments using red iron oxide have excellent advantages such as high safety and light resistance.

[0003]

However, red pigments using the above-mentioned red iron oxide are limited to brownish red which is a color peculiar to the iron oxide, and have various red-based hues like organic pigments. A red pigment having the appearance color of was not obtained. Of course, it is also possible to change the color tone of the pigment by, for example, coating the surface of the mica particles with red iron oxide and an inorganic substance having another color, but in this case, a mixture of a plurality of types of substances is coated on the surface of the mica particles. In this case, there is a problem that the coating operation itself is difficult, and the light is remarkably reduced because light is absorbed by each substance, and the color gradually approaches black. The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a red pigment including only an inorganic substance having a high brightness and a bright red color tone, and a method for producing the same. is there.

[0004]

Means for Solving the Problems To achieve the above object, the present inventors have conducted intensive studies, and as a result, formed a red iron oxide on a flake, and coated an aluminum compound on a surface of the plate-shaped red iron oxide with a predetermined thickness. The present inventors have found that an outer appearance color different from the color tone of the red iron oxide itself can be obtained by coating with, and the present invention has been completed.

[0005] The red pigment according to claim 1 is a plate-like iron oxide particle in which an iron oxide layer is formed on a plate-like particle, and an aluminum compound containing aluminum oxide formed on the plate-like iron oxide particle. And an optical layer thickness of the iron oxide layer of the plate-like iron oxide particles is 6
0 to 350 nm, and the optical layer thickness of the aluminum compound layer is 150 to 500 nm. Contract
The method for producing a red pigment according to claim 2, wherein the iron oxide to be coated on the plate-shaped particles is deposited from a coating bath containing a precursor of the iron oxide such that the amount of the iron oxide is 20 to 100% by weight. The plate-like particles are coated with iron oxide by a method to form iron oxide-coated plate-like particles, and the amount of the aluminum compound containing aluminum oxide to be coated with respect to the iron oxide-coated plate-like particles is 15 to 60% by weight. In such a manner, the iron oxide-coated plate-like particles are coated with an aluminum compound by a deposition method from a coating bath containing the aluminum compound precursor containing the aluminum oxide to form aluminum compound-coated iron oxide-coated plate-like particles, the aluminum compound-coated iron oxide-coated plate-like particles were calcined at 100 to 900 ° C., the aluminum
Optical layer of iron oxide layer of iron oxide coated plate-like particles coated with compound
The aluminum compound coating having a thickness of 60 to 350 nm;
Optical properties of aluminum compound layer of iron oxide coated plate-like particles
It is characterized in that the layer thickness is 150 to 500 nm.

Hereinafter, the configuration of the present invention will be described in more detail. In the present invention, in order to obtain plate-like iron oxide particles,
Muscovite, biotite, phlogopite, synthetic mica, mica, lithia mica, talc, kaolin, sericite, platy silica, platy alumina, platy titanium dioxide, mica titanium
It is preferable that the plate-like particles are coated with iron oxide as a plate-like particle based on a minium powder, a stainless steel powder or the like. Further, commercially available iron oxide-coated mica can be used as an intermediate of the red pigment of the present invention.

The particle size of the plate-like particles is not particularly limited. However, when used as a pigment for general industrial products such as cosmetics, the particle size should be about 1 to 50 μm and the shape should be as flat as possible. However, it is preferable because a beautiful color tone is easily developed. The iron oxide used in the plate-like particles coated with iron oxide, which is an intermediate in obtaining the red pigment according to the present invention, refers to red iron such as α-Fe ₂ O ₃ and γ-Fe ₂ O _3. Refers to brown iron oxide. In the present invention, these may be coated alone or in the form of a mixture of two or more. In addition, hydrated iron oxide FeO (O
H) or black iron oxide (Fe ₃ O ₄ ), which may be oxidized to Fe ₂ O ₃ in the final firing step.

Here, it is preferable that the amount of iron oxide to be coated is such that the optical layer thickness of the iron oxide layer is 60 to 350 nm, and specifically, the plate-like particle diameter is 1 to 350 nm. 50 μm
In the case of 20 to 100% by weight of the plate-like particles,
%, Preferably 30 to 80% by weight. When the amount of the coated iron oxide is less than 20% by weight, the color tone of the red system tends to be weak, and when the amount exceeds 100% by weight, the color tone of the iron oxide is emphasized and a brown color peculiar to the iron oxide is cast. It is not preferable because of color tone. Here, the optical layer thickness means a value obtained by multiplying a geometric layer thickness by a refractive index.

On the other hand, as long as the aluminum compound used in the present invention contains aluminum oxide Al ₂ O ₃ as an essential component, it is also possible to use hydrated aluminum oxide Al ₂ O ₃ (H
₂ O), Al ₂ O ₃ (3H ₂ O), aluminum hydroxide and the like may be mixed. In the red pigment according to the present invention, the amount of the aluminum compound to be coated is preferably such that the optical layer thickness of the aluminum compound layer is 150 to 500 nm, and the plate-like particle diameter is 1 to 50 μm. In this case, the amount of the aluminum compound is 15 to 60% by weight, preferably 20 to 40% by weight, based on 100% by weight of the iron oxide-coated plate-like particles as the intermediate. If the amount of the aluminum compound to be coated is less than 15% by weight with respect to 100% by weight of the iron oxide-coated plate-like particles as an intermediate, the color tone originally possessed by iron oxide cannot be adjusted.
If it exceeds 0% by weight, a significant decrease in saturation occurs. The amount of the aluminum compound to be coated is 25% with respect to 100% by weight of the plate-like particles coated with the intermediate iron oxide.
When the content is less than 25% by weight, an orange color tone is obtained. When the content is 25 to 40% by weight, a blue-red color tone is obtained.

In the step of coating the iron oxide-coated plate-like particles, which are intermediates of the present invention, with an aluminum compound, the final firing temperature is 100 to 900 ° C., preferably 300 to 900 ° C.
800 ° C. If the sintering temperature exceeds 900 ° C., particle aggregation occurs, which is not preferable.

As a method for producing the red pigment according to the present invention, the following method can be mentioned. That is, as a method of coating the surface of the plate-like particles with iron oxide, plate-like particles such as a commercially available muscovite pigment are dispersed in water, and the dispersion is treated with chloride (I)
Aqueous solutions of iron salts such as iron, iron chloride (II), iron sulfate (I), iron sulfate (II), iron nitrate (I), and iron nitrate (II), and alkali aqueous solutions such as sodium hydroxide and potassium hydroxide Is the pH
While keeping the temperature constant, and coated with hydrated iron oxide by neutralization and decomposition.
Or by dispersing a commercially available muscovite pigment in water and adding it to iron (I) chloride, iron (II) chloride, iron (I) sulfate, iron (II) sulfate, iron (I) nitrate , An aqueous solution of an iron salt such as iron (II) nitrate and urea are added in advance, and
A method of heating to 0 to 100 ° C. to neutralize and decompose, coating with hydrated iron oxide, and then baking at a high temperature of 150 to 800 ° C., evaporating the iron compound at a high temperature and depositing it directly on plate-like particles. Method and the like.

Further, as a method for coating the intermediate of the present invention coated with iron oxide with an aluminum compound, the following method is exemplified. That is, the iron oxide-coated plate-like particles are dispersed in water, and an aluminum salt aqueous solution such as aluminum chloride, aluminum sulfate, and aluminum nitrate is added thereto.
Alkaline solutions such as sodium hydroxide and potassium hydroxide are simultaneously added little by little while keeping the pH constant.
A method of coating with hydrated aluminum oxide by neutralization decomposition and baking it at a high temperature of 150 to 700 ° C, or dispersing iron oxide-coated plate-like particles in water and adding aluminum chloride, aluminum sulfate, aluminum nitrate, etc. An aqueous solution of aluminum salt and urea are added in advance, and
A method of heating to 0 to 100 ° C. for neutralization and decomposition, coating with hydrated aluminum oxide, and baking at a high temperature of 150 to 800 ° C. is exemplified.

[0013]

As described above, the red pigment according to the present invention uses an aluminum compound to adjust the color tone of red iron oxide. That is, a general pigment uses a substance that absorbs only light of a specific wavelength and reflects light of another wavelength. When the pigment is irradiated with white light, which is an aggregate of light of various wavelengths, only the light component of the specific wavelength is absorbed, and the color tone of the pigment is defined by the reflected light having a complementary color relationship with the absorbed light. . That is, in red iron oxide, brownish red, which is a color unique to iron oxide, corresponds to the reflected light. Then, in the case of a general concept of a pigment, it is necessary to add a substance that absorbs light in another wavelength range in order to adjust the color of the pigment.

However, in this case, the absorption wavelength band is expanded, and the color tone of the pigment gradually approaches an achromatic color, and the saturation decreases. Therefore, the present inventors have adjusted the color tone of the iron oxide-coated mica using the interference effect of light. That is, the plate-like particle surface is coated with iron oxide,
Further, when the iron oxide-coated particles are coated with an aluminum compound, the pigment structure is configured as schematically shown in FIG. Here, the mica 10 is in the form of a flake, and the iron oxide 12 is coated in a thin layer around the flake. And iron oxide layer 1
2 is further coated with an aluminum compound 14 containing aluminum oxide. The mica 10 and the aluminum compound 14 are white and have high light transmittance, and the iron oxide layer 12 is brownish red as described above.

When such pigment is irradiated with white light 16, a part of the irradiated light 16 becomes white light 18 reflected on the surface of the aluminum compound layer 14, while the surface of the iron oxide layer 12 and the surface of the mica 10 The reflected lights 20 and 22 are partially absorbed by iron oxide in a part of the wavelength range, and become brownish red light. Then, the red reflected lights 20 and 22 and the white reflected light 18 cause interference, and only the light having a specific wavelength of the red reflected lights 20 and 22 is emphasized, so that reflected light (interference light) having a sharp color tone is obtained. It is. That is, as shown in FIG. 2, for example, white reflected light 18 and red reflected lights 20 and 22
Has an optical path difference depending on the thickness of the aluminum compound layer 14. Then, in the reflected lights 20 and 22, FIG.
And the light component of the same wavelength in the reflected light 18 due to the optical path difference (L = about twice the aluminum compound layer), the peaks of the light components of the red reflected lights 20 and 22 The portion is located in the valley portion of the light component of the white light 18, and the two cancel each other out and disappear as shown in FIG.

However, as shown in FIG. 1D, in the case of a light component having a wavelength half that of the above-mentioned (A), the red reflected light 20
Each light component of the white reflected light 22 and the light component of the white reflected light 18 are shifted by one wavelength, and their peaks and valleys overlap, and amplitude amplification is performed as shown in FIG. As a result, the red reflected light 20, 2
Only the light of the specific wavelength 2 is emphasized, and a much sharper color tone can be obtained as compared with the reflected light of the iron oxide itself. Although the red pigment according to the present invention is coated with an aluminum compound, the aluminum compound has an extremely high light transmittance, and as a whole, the reflected light 18, 2
The total light amount of 0,22 does not decrease so much, and the saturation does not decrease remarkably as in the case where a plurality of types of pigment substances are mixed as in the related art.

In the present invention, since the color tone is adjusted by the interference as described above, the optical path difference for causing the interference is an important condition. As is apparent from FIG. 2, when the optical path difference is a half wavelength of the light wavelength, the light intensity in the wavelength range is substantially reduced, and when the optical path difference is the same as the light wavelength or an integral multiple thereof. The light intensity in this wavelength range increases substantially substantially. Therefore, the optical path difference must be adjusted so as to adjust the intensity of light having a wavelength in the visible light range.

As described above, according to the red pigment according to the present invention, by utilizing light interference depending on the thickness of the aluminum compound layer 14, the red pigment excellent in color tone such as lightness and chroma is obtained. Pigments can be obtained. Moreover, since the red pigment is basically formed of an inorganic substance composed of an iron oxide and an aluminum compound, it has stability, safety, light resistance, acid resistance, alkali resistance, solvent resistance, heat resistance, and the like. Is also very good.

[0019]

EXAMPLES Hereinafter, the red pigment according to the present invention and a method for producing the same will be described in more detail with reference to Examples. Note that the present invention is not limited to these examples. In addition, all the compounding amounts are shown by weight%. Relationship Between Color Tone and Layer Thickness First, the relationship between the layer thickness of the aluminum compound layer and the color tone characteristic of the present invention will be described. Here, red pigments having various aluminum compound layer thicknesses were formed by the following method, and the color tone was examined. Commercially available muscovite (average particle size 30
μm) was dispersed in 500 ml of water, and a predetermined amount of 10 wt% ferric chloride (hexahydrate) was added at a rate of 5 ml per minute while heating and stirring at 90 ° C. At this time, a 0.5N aqueous sodium hydroxide solution is added at the same time, and p
H is maintained at 4.5-5.0. The product was filtered, dried and calcined at 500 ° C. for 2 hours to obtain iron oxide-coated mica.

Next, 100 g of the obtained iron oxide-coated mica, a predetermined amount of aluminum sulfate (14 hydrate) and 200 g of urea
Was dispersed in 1000 ml of water, heated and stirred at the boil for 4 hours, washed with water, filtered and dried.
Calcination at ℃ yielded aluminum oxide-coated iron oxide-coated mica. The color tone was measured by weighing 5 g of a red pigment in a cell for measuring the color tone of a powder made of quartz, sufficiently orienting it, and pressing it at a constant pressure to prepare a sample for measurement. Next, the color of the measurement sample was measured with a spectrophotometer (Hitachi C-2000). Each layer thickness is indicated by an optical layer thickness.

[0021]

[Table 1] Ferric chloride content 33,75 g Iron oxide layer thickness 30 nm {Amount of aluminum sulfate (g) 31 95 160 220 315 380}ア ル ミ ニ ウ ム Aluminum oxide layer thickness (nm) 0 50 150 250 350 500 600 600 ─────────────────────────────────── HV HV / C 3.0R 3.8R 4.8R 3.9 R 4.0R 4.5R 3.0R 3.8 4.3 4.98 5.16 5.18 5.0 4.44 /6.80 /6.81 /7.06 /7.62 /7.40 /6.60 /1.00 ─────────── ─────────────────────────

[0022]

[Table 2] Ferric chloride amount 45.0 g Iron oxide layer thickness 60 nm {Amount of aluminum sulfate (g) 31 95 160 220 315 380}ア ル ミ ニ ウ ム Aluminum oxide layer thickness (nm) 0 50 150 250 350 500 600 600 ─────────────────────────────────── ─ HV / C 3.5R 3.7R 8.4R 2.3R 7.4R 7.0R 5.3R 3.34 3.60 4.42 4.81 4.80 4.69 4.00 /6.92 /6.95 /7.78 /8.31 /8.16 /7.54 /6.06 ─────────── ─────────────────────────

[0023]

[Table 3] Ferric chloride content 120 g Iron oxide layer thickness 70 nm量 Amount of aluminum sulfate (g) 31 95 160 220 315 380 酸化 Oxidation Aluminum layer thickness (nm) 0 30 150 250 350 500 600 600 HV / C 3.5R 3.7R 8.5R 0.3R 6.4R 5.7R 3.5R 3.19 3.30 4.08 4.80 4.90 4.42 3.48 /6.90 /6.90 /7.88 /8.48 /8.22 /7.50 /6.10 ───────────── ───────────────────────

[0024]

[Table 4] Amount of ferric chloride 200g Iron oxide layer thickness 250nm量 Amount of aluminum sulfate (g) 31 95 160 220 315 380 酸化 Oxidation Aluminum layer thickness (nm) 0 50 150 250 350 500 600 HV HV / C 3.5R 3.7R 7.1R 9.3RP 6.1R 5.3R 3.0R 3.00 3.12 4.01 4.44 4.81 4.01 3.08 /7.00 /7.05 /8.10 /8.52 /8.33 /8.14 /6.22 ───────────── ───────────────────────

[0025]

[Table 5] Ferric chloride content 260 g Iron oxide layer thickness 350 nm {Amount of aluminum sulfate (g) 0 31 95 160 220 315 380} Aluminum oxide layer thickness (nm) 0 50 150 250 350 500 600 600 HV / C 3.5R 3.8R 8.0R 0.8R 6.8R 6.0R 4.0R 2.80 2.84 3.23 4.12 4.36 3.43 2.80 /6.85 /6.86 /7.60 /8.28 /8.16 /7.40 /6.18 ──────────── ────────────────────────

[0026]

[Table 6] Ferric chloride content 350 g Iron oxide layer thickness 450 nm {Amount of aluminum sulfate (g) 0 31 95 160 220 315 380} Aluminum oxide layer thickness (nm) 0 30 150 250 350 500 600 600 HV / C 3.8R 4.0R 4.5R 4.1R 4.0R 3.9R 3.1R 2.40 2.42 2.72 3.02 3.18 3.06 3.06 /6.20 /6.44 /6.56 /6.62 /6.46 /6.10 /5.68 ──────────── ────────────────────────

As described above, according to the present invention, if the iron oxide layer is less than 60 nm, a sufficient red color cannot be obtained. If the thickness of the aluminum oxide is less than 150 nm, the color tone of the iron oxide is emphasized, and the adjustment cannot be performed. Thus, by coating a brownish red iron oxide-coated mica with a colorless or white aluminum oxide, it is possible to obtain a red-based pigment having extremely sharp and various colors.

Example 1 100 g of commercially available muscovite was dispersed in 500 ml of water.
1300 ml of 10 wt% ferric chloride (hexahydrate) was added at a rate of 5 ml per minute while heating and stirring at ℃. At this time, a 0.5N aqueous sodium hydroxide solution is simultaneously added to maintain the pH at 4.5 to 5.0 until the reaction is completed. And
The product was filtered, dried and calcined at 500 ° C. for 2 hours to obtain 136 g of iron oxide-coated mica. Next, 100 g of the obtained iron oxide-coated mica, aluminum sulfate (14 hydrate) 175
g and 200 g of urea were dispersed in 1000 ml of water, heated, stirred in a boiling state for 4 hours, washed with water, filtered, dried, and calcined in air at 500 ° C. to obtain 127 g of aluminum oxide-coated iron oxide-coated mica. Obtained. The resulting powder had a vivid purple-red appearance and gloss.

Example 2 Commercially available iron oxide-coated mica (Iriodin 524 from Merck) 10
0 g, 233 g of aluminum sulfate (14 hydrate) and 250 g of urea were dispersed in 1000 ml of water, heated, stirred at the boil for 4 hours, washed with water, filtered and dried.
It was calcined at 400 ° C. in the air to obtain 138 g of aluminum oxide-coated iron oxide-coated mica. The resulting powder had a vivid blue-red appearance and gloss.

Example 3 100 g of commercially available muscovite was dispersed in 500 ml of water, 20 ml of 2M titanyl sulfate was further added, and this condition was maintained for 2 hours while heating and stirring at 90 ° C. After washing with water, filtration and drying, the mixture was calcined at 800 ° C. to obtain 101 g of mica coated with titanium dioxide. Next, the obtained titanium dioxide-coated mica 3
0 g was dispersed in 300 ml of water, and 1000 ml of 10 wt% ferric chloride (hexahydrate) was added to 5 ml while heating and stirring at 90 ° C.
It was added at a rate per minute. At this time, a 0.5N aqueous sodium hydroxide solution was added at the same time to adjust the pH to 4.5 until the reaction was completed.
５5.0. And after filtering and drying the product,
Calcined at 500 ° C for 2 hours to obtain iron oxide-coated mica titanium 5
7.0 g were obtained. Further obtained iron oxide-coated mica titanium 5
0 g, 100 g of aluminum chloride (hexahydrate) and 100 g of urea were dispersed in 500 ml of water, heated, stirred at the boil for 4 hours, washed with water, filtered, dried and calcined at 400 ° C. in the atmosphere. Thus, 61 g of titanium oxide coated with aluminum oxide and iron oxide was obtained. The obtained powder had a vivid orange color and gloss.

Example 4 Commercially available iron oxide-coated mica (Iriodin 524 from Merck) 10
0 g, 260 g of aluminum sulfate (14 hydrate), 20 g of ferric chloride, and 300 g of urea were dispersed in 1000 ml of water, heated, stirred at the boil for 4 hours, washed with water, filtered and dried. It was calcined at 400 ° C. in the air to obtain 146 g of aluminum oxide-coated iron oxide-coated mica. The resulting powder had a vivid blue-red appearance and gloss.

Example 5 Commercially available iron oxide-coated mica (Iriodin 524 from Merck) 50
g of water was dispersed in 500 ml of water, and heated to 90 ° C. while stirring and a 10 wt% aluminum sulfate (14 hydrate) aqueous solution 2 was added.
3.000 ml with 1N aqueous sodium hydroxide solution to pH 4.
The solution was added at a rate of 10 ml / min while maintaining the pH at 5 to 5.0, washed with water, filtered, dried, and then calcined at 400 ° C. in the atmosphere to obtain 65 g of aluminum oxide-coated iron oxide-coated mica. The resulting powder had a vivid blue-red appearance and gloss.

Example 6 100 g of commercially available mica titanium (Iriodin 215 manufactured by Merck)
Was dispersed in 500 ml of water, and 2000 ml of 10 wt% ferric chloride (hexahydrate) was added to 5 ml while heating and stirring at 90 ° C.
It was added at a rate per minute. At this time, a 0.5N aqueous sodium hydroxide solution was added at the same time to adjust the pH to 4.5 until the reaction was completed.
５5.0. After filtering and drying the product, 5
Fired at 00 ° C for 2 hours, 160g of iron oxide coated mica titanium
I got Next, 100 g of the obtained iron oxide-coated mica titanium,
175 g of aluminum sulfate (14 hydrate) and urea 20
0 g was dispersed in 1000 ml of water, which was heated, stirred at the boil for 4 hours, washed with water, filtered, dried, and then dried in air.
Calcination was performed at 00 ° C. to obtain 123 g of aluminum oxide-coated iron oxide-coated mica titanium. The obtained powder had a vivid orange color and gloss.

Example 7 100 g of commercially available kaolinite, ferric chloride (hexahydrate)
100 g and 150 g of urea were dispersed in 1000 ml of water, heated and stirred at 90 ° C. for 4 hours, and the product was filtered.
It was dried and then calcined at 500 ° C. for 2 hours to obtain 127 g of iron oxide-coated kaolinite. Next, 100 g of the obtained iron oxide-coated kaolinite, 120 g of aluminum sulfate (14 hydrate) and 250 g of urea were dispersed in 1000 ml of water, heated, stirred at the boil for 4 hours, washed with water, filtered, After drying, it was calcined at 500 ° C. in the air to obtain 116 g of aluminum oxide-coated iron oxide-coated kaolinite.
The resulting powder had a yellow-orange appearance.

The material properties of the red pigments of the present invention obtained in the above Examples 1 to 7 were tested. For comparison, pigment properties of colored titanium mica (iron oxide coated mica and carmine-added mica titanium) commercially available from Mearl, USA were similarly tested. Test items were appearance color tone, acid stability,
They are alkali stability, light stability, and heat stability. Test methods and test results are shown below. Appearance Color Tone 5 g of the red pigment of the present invention and commercially available colored mica titanium were weighed into a quartz powder color tone measurement cell, sufficiently oriented, and pressed at a constant pressure to prepare a measurement sample. Next, the measurement sample was analyzed using a spectrophotometer (Hitachi C-20).
00). An average value of three measurements was taken. Acid Stability 1.5 g of the red pigment of the present invention and commercially available colored mica titanium are placed in test tubes each containing 50 ml of a stoppered stopper, 30 ml of a 2N hydrochloric acid aqueous solution is added thereto, and the mixture is dispersed. After 24 hours, the color tone was visually observed. Alkali stability 1.5 g of the red pigment of the present invention and commercially available colored mica titanium are each placed in a test tube containing 50 ml of a stopper, and 30 ml of a 2N sodium hydroxide aqueous solution is added thereto, followed by dispersion.
It was left standing in a test tube stand, and the color tone after 24 hours was visually observed. Light Stability A red-based pigment of the present invention and 2.5 g of commercially available colored mica titanium were each formed into a square aluminum inner plate having a thickness of 3 mm and a side of 20 mm, and this was irradiated with a xenon lamp for 30 hours. The color tone before and after irradiation is measured using a spectrophotometer (Hitachi C-20)
00), the color difference before and after irradiation (ΔE)
I asked. Heat stability 3.0 g of the red pigment of the present invention and commercially available colored mica titanium are weighed into a 20 ml magnetic crucible, respectively.
Heat treatment was performed at 400 ° C. in the air for 2 hours. The color tone before and after the treatment was measured with a spectral colorimeter (Hitachi C-2000), and the color difference (ΔE) before and after irradiation was determined from the colorimetric values. Table 8 shows the results of each stability test.

[0036]

Table 7 Pigment used in Comparative Example 比較 Comparative Example 1 Croisone Rouge Flambe TiO ₂ + Mica + Fe ₂ O ₃比較 Comparative Example 2 Croisone Red TiO ₂ + Mica + Carmin── ───────────────────────────────

[0037]

[Table 8] Color tone and stability test results ──────────────────────────────────── Color tone HV / C Acid stability Alkaline stability Light stability Thermal stability ──────────────────────────────────── Implementation Example 1 0.7R 4.0 / 8.3 ◎ ◎ 0.71 0.81 2 8.5RP 4.5 / 8.2 ◎ ◎ 0.74 0.65 3 7.0R 4.0 / 9.0 ◎ ◎ 0.82 0.74 4 9.0RP 4.2 / 8.2 ◎ ◎ 0.77 0.35 5 0.5R 4.5 / 8.0 ◎ ◎ 0.60 0.55 6 7.5R 4.8 / 8.1 ◎ ◎ 0.79 0.75 7 8.0R 3.8 / 7.1 ◎ ◎ 0.65 0.88 ─比較 Comparative Example 1 2.8R 4.9 / 6.9 ○ ◎ 0.77 0. 83 2 2.3RP 5.4 / 7.5 × × 22.1 40.3 ─────────────────────── ──────────── Evaluation criteria: ◎ Highly stable without any discoloration ○ Slightly discolored visually but still good stability × Discolored and stable Low

From the results shown in Table 2, the red pigment, which is a product of the present invention, can adjust the color tone from yellow-red to blue-red by changing the amount ratio of iron oxide and / or aluminum compound coating the plate-like particles. It can be understood that the adjustment can be made.
The chroma of the red pigment of the present invention is about the same as or higher than that of croizone red of Comparative Example 2 to which an organic substance is added. Very few inorganic pigments having a saturation comparable to that of organic pigments are very rare, and the superior color tone of the plate-shaped red composite material of the present invention over commercially available inorganic pigments is apparent. Further, from the results shown in Table 2, the red pigment of the present invention has almost the same or higher stability as the commercially available iron oxide-coated mica of Comparative Example 1. In particular, the acid stability is superior to commercially available iron oxide-coated mica. This is because iron oxide is eluted by acid in commercially available iron oxide-coated mica, whereas the red pigment of the present invention has a particle surface completely covered with aluminum oxide having excellent acid stability. is there. In addition, the titanium mica of Comparative Example 2 to which carmine was added was inferior in discoloration deterioration under severe conditions due to poor stability of carmine.

[0039]

As described above, according to the red pigment of the present invention, by coating the surface of the plate-like iron oxide with an aluminum compound containing aluminum oxide, a high chroma from orange to blue-red is obtained. A red pigment having a continuous color tone and excellent stability can be obtained.

[Brief description of the drawings]

FIG.

FIG. 2 is an explanatory diagram showing a color tone adjusting action of a red pigment according to the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiko Sato 1050 Nippa-cho, Kohoku-ku, Yokohama-shi, Kanagawa Shiseido Co., Ltd. First Research Center (56) References JP-A-1-263157 (JP, A) JP-A-64-85255 (JP, A) JP-A-62-285595 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09C 1/00-3/12

Claims (2)

(57) [Claims] A plate comprising an iron oxide layer formed on plate-like particles.
Iron oxide particles and acid formed on the plate-like iron oxide particles
Al consisting of an aluminum compound containing aluminum halide
An optical layer thickness of the iron oxide layer of the plate-like iron oxide particles is 60 to 350 nm, and an optical layer thickness of the aluminum compound layer is 150 to 500 nm. Red pigment. 2. The method according to claim 1, wherein said plate-like particles are oxidized from said coating bath containing a precursor of said iron oxide by a deposition method so that the amount of iron oxide to be coated on said plate-like particles is 20 to 100% by weight. Iron is coated to form iron oxide-coated plate-like particles, and the iron oxide-coated plate-like particles are oxidized so that the amount of aluminum compound containing aluminum oxide to be coated is 15 to 60% by weight. An aluminum compound is coated on the iron oxide-coated plate-like particles by a deposition method from a coating bath containing an aluminum compound precursor containing aluminum to form aluminum compound-coated iron oxide-coated plate-like particles; 10 particles
Baking at 0 to 900 ° C., and the optical layer thickness of the iron oxide layer of the aluminum compound-coated iron oxide-coated plate-like particles is 60 to 35.
0 nm, the optical layer thickness of the aluminum compound layer of the aluminum compound-coated iron oxide-coated plate-like particles is 150 to
A method for producing a red pigment, which has a thickness of 500 nm.